Conduit for electric wires.



n. u. MURPHY, CONDUIT FOR ELECTRIC WIRES APPLICATION FILED SEPT-19,1913- Patented J an. 22, 1918.

WITN 555:5 W

UNITED STATES PATENT OFFICE,-

1 DANIEL HAYES MURPHY, 0F PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO THE AMERI- CAN CONDUIT MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

CONDUIT FOR ELECTRIC WIRES.

Specification of Letters Patent. Patented J an, 22, 1918,

Application filed September 19, 1913. Serial No. 790,645.

To all whom it may concern:

Be it known that I, DANIEL HAYES MUR- PHY, a resident of Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Conduits for Electric \Vires, of which the following is a specification.

This invention relates to pipes, tubes,etc., and fittings therefor, and which are used for various purposes, such as conduits for wires and the like.

The object of the invention is to provide an iron or steel conduit having on either or both of its surfaces a combination coating which thoroughly protects the steel or iron against rust or corrosion by chemical reagents, and also against electrolytic action when the conduit is immersed in water.

Lead coatings, such as have been used for protecting coatings, are very resistant to all corrosive chemical agents, whether acid or alkali, and pipe coated therewith will not corrode even if pin holes are present. Lead, however, is not a good protective agent against electrolytic action and if a pipe coated therewith is immersed in water, the iron or steel base is liable to rust or be eaten away. Zinc coatings form a good protection against electrolytic action, as the zinc is electropositive to iron or steel, but zinc will not successfully withstand corrosive agents, such as acids or alkalis. While copper coatings have also been used they are too expensive if applied in amounts suflicient to afford good protection.

My invention is designed to overcome all the foregoing objections to coated conduits and provide an improved conduit having a combination coating of two different metals superposed upon each other, at least one of which is electropositive to iron or steel, and which coating thoroughly protects the iron or steel against both chemical and electrolytic action.

In the drawings, Figure 1 represents an elevation, partly broken out and in section, of an iron or steel tube having a coating embodying the invention; and Fig. 2 is a transverse section of said tube.

The body 1 of the tube, pipe or fitting is of iron or steel, asordinarily. Either or both of its surfaces are provided with a combination coating consistingv of two superposed layers of dissimilar metals. These layers are preferably appliedv electrolytior alkalis.

ing an electrodeposited cally, and either layer may be on top, so long as both are used. One of the layers, such as layer 2, is formed of 'a cheap, noncorrodible metal, which may be electronegative or 'electropositive to iron or steel, and is shown as lead, which is 'electronegative. This layer is preferably of sufficient thickness to form an eificient protection against corrosion by chemical reagents, such as acids The other layer 3 is formed of a different metal which can be readily applied either directly to the iron or steel or upon the layer 2 of'lead or other metal. It is also a metal which is electropositive to iron or steel,-so,that in case the pipe is'subjected I. to immerslon in water, the electrolytic action causes deposition of said metal onthe iron,

steel or lead, and not the reverse action. One such metal is zinc, which if applied eitherdirectly to the iron or steel or to the lead wholly prevents electrolytic decomposition of the iron or steel. The coating of the electronegative metal, such as lead, is in all cases of suflicient thickness to thoroughly protect the pipe against corrosion by acids, alkalis, or other corrosive agents. The electropositive metal, su h as zinc, may be applied in layers of any thickness, but preferably is a mere flash. By its mere presence it furnishes electrolytic protection and largely prevents electrolytic decomposition of the iron or steel. The combination coating described forms an efficient protection against corrosion or attack, while if the zinc is applied over the lead it also fills up all pin holes and scratches and generally improves and brightens the appearance of the conduit.

When only one surface of the pipe or conduit is coated as described the other surface may be. left uncoated or may be provided with any other suitable or preferred coating, such as an enamel coating, which face.

What I claim is:

1. A new article of manufacture, comprising an iron or steel conduit having its surfaces provided. with an acid-resisting non-corrosive combination coating comprislayer of substantially pure lead and a superposed electrodeposited layer of substantially pure zinc. I v

2. A new article of manufacture, compr1s-.

-stantially pure lead of suflicient thickness to 'withstand chemical corrosion, and a superposed electrodeposited layer of substantially pure zinc'filling the recesses in the layer of lead and of suflicient thickness to set my hand.

prevent corrosion.

3. The method of providing an iron or steel conduit with an acid-resisting noncorrosive coating which will not be subject to electrolysis, Which comprises electrodepositing upon the surfaces of said conduit a relatively thin layer of substantially pure lead and subsequently electrodepositing upon said'lead covering a thin layer of substantially pure zinc to fill the minute recesses in the lead covering and provide a non-corrosive outer coating WhlCh Will prevent electrolysls.

In testimony whereof I have hereunto DANIEL HAYES MURPHY. Witnesses: 1

F. W. WINTER,

GLENN H. LERESOHE. 

